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8.4 Colors in PostScript

Nevertheless, here are some tips on how to design your PostScript styles. It is strongly recommended to use gray.pro or color.pro as a template.

There are two PostScript instructions you might want to use in your new PostScript prologue:

setgray

this instruction must be preceded by a number between 0 (black) and 1 (white). It defines the gray level used.

setrgbcolor

this instruction must be preceded by three numbers between 0 (0 %) and 1 (100%). Those three numbers are related to red, green and blue proportions used to designate a color.

a2ps uses two higher level procedures, BG and FG, but both use an argument as in setrgbcolor. So if you wanted a gray shade, just give three times the same ratio.